British ISP British Telecom implemented a new system where they will actively search and clean PCs from customers who have been found sending spam, with extra care to those who are believed to be a part of zombie networks which are also used in DDoS attacks.

Once such a system have been found the ISP either helps the customer to clean their system, or terminates the account, depending on whether the customer knowingly sent spam, or has been infected by malicious software.